1. Field of the Invention
This invention relates to a transmission apparatus having an endless transmission linking loop applied over first and second rotating members, so as to transmit a rotation between the first rotating member and the second rotating member. More particularly, the present invention relates to a transmission apparatus used in a bicycle, having an endless transmission linking loop applied over first and second rotating shafts so as to transmit a rotation from the first rotating shaft to the second rotating shaft, as used in a bicycle.
2. Description of the Background Art
Many different types of transmission assemblies are known, and are commercially available. One example of a known transmission apparatus, for use on a bicycle, is disclosed in Japanese Utility Model Application No. Sho 59 (1984)-172882, as well as Japanese Utility Model Laid-Open No. Sho 61 (1986)-87190, for example.
The transmission apparatus disclosed in Japanese Utility Model Application No. Sho 59 (1984)-172882 is comprised of a single-stage or multi-stage front chain gear device drivingly connected to a main drive shaft; a multi-stage sprocket device drivingly connected to the rear hub and having more stages than that of the front chain gear device; and a chain applied over the front chain gear device and the multi-stage sprocket device. Then, in the case of performing a transmission gear change, the chain is transferred from one sprocket of the multi-stage sprocket device to other sprocket by the rear derailleur, operated by an operating wire.
In the case of the transmissions taught by these references, there occurs a possibility that the chain is removed sometimes from either the chain gear or the sprocket, while the chain is inclined in respect to a plane crossing at a right angle with an axial direction when the chain is applied over the chain gear and the sprocket placed in an axial different direction because the chain gear of the front chain gear device cannot be moved axially and the multi-stage sprocket device constituted by a plurality of sprockets axially arranged shows a large axial width size. Then, when there remains a small clearance between the front chain gear device and the multi-stage sprocket device, the chain is removed more easily because inclination of the chain in respect to the right angle crossing plane becomes larger.
The present invention has been invented in view of the circumstances as described above, and it is an object of the present invention to provide a transmission apparatus capable of preventing the endless transmission linking loop from being removed from the rotating member even in the case that there remains a small inter-axis distance between the two rotating shafts to which each of the two rotating members having the endless transmission linking loop wound around themselves is drivingly connected.
It is another object of the present invention to minimize or reduce the size of the transmission apparatus.
Although the known devices have some utility for their intended purposes, there is still a need to provide an improved transmission which eliminates the traditional chain drive system for use with a bicycle. More particularly, there is a need for an improved bicycle transmission including components designed to solve the above-mentioned problems.